Dispatching system



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m NONNA Patented July 14, 1936 PATENr oEFlcE DISPATCHING SYSTEM jHarry E. Hershey, Oak Park, and Alfred H. B elliveau, Chicago, Ill., assignors, by mesne assignments, to Associated Incl, Chicago,

Electric Laboratories,

Ill., a, corporation of Delaware Application September 30, 1931, Serial No. 566,078 i claims.' (o1. Irl-e353) The present invention relates in general to dispatching systems, but is particularly concerned in the provision of a dispatching system in which any nu-mber of field stations may be interconnected, by a single set of line conductors, to' a dispatchers station.

Among the objects of the invention are: to provide a system of this general character with facilities whereby a vdispatcher may rapidly select and operate one of a large plurality of pieces of equipment located in anyremote field station and whereby, responsive to the'operation of a piece of equipment at any eld station, its operation is promptly registered at the dispatchers station. l

A further feature of` the invention has to do with the provision ofcirouits and apparatus for enabling thedispatcher toV select and operate equipment as mentioned at the'same time that previously operated equipment is causing the registration of its operation to occur at the dispatchers station. l

Other features and objects have to do with the provision of circuits and apparatus in a system of the foregoing character which can also be arranged so that the dispatcher is prevented from selecting and operating a piece of eld equipment while a field station is transmitting a recording indicationor` signal back to the dispatchers station. Y

The form of the invention employed will, of course, depend upon the type of service required. Either system,- however, has considerable utility as a train dispatching system, and in systems for the control of substation apparatus of power and fuel distribution systems. In illustrating and describing the invention, the substation equipment is represented as ay customers equipment, which obviously, may comprise any piece of apparatus or device which may be operated.

The invention is illustrated in thirteen sheets of drawings, comprising Figs. 1 to 13, respectively. Figs. 1 to 4, inclusive, when arranged' withr Fig. 1 immediately above Fig. 2 and with Fig. 3 to the right of Fig. 2 and with Fig. 4 to the right of Fig. 3, respectively, diagrammatically illustrates the apparatus and circuits of one' el'd station of the system. The Figs. 5 to4 8, inclu-- sive, when arranged with Fig. `5 immediately above Fig. 6 and with Figs. 7 and8 placed at the right of Figs. 6 and 5, respectively; diagrammatically illustrate the circuits and apparatus of the' dispatchers station of the system.

Figs. 11, l2, 13, and ei,v when arranged with Fig. 4. to the right of Fig. 13, Fig. 12 to the' leftV of Fig. 13, and with Fig. 11 immediately above Fig. 12, diagrammatically illustrate the apparatus and circuits of a eld station of an alternative form of the system. Figs.` 5, 8, 9, and 10, when arranged withFig. 8 immediately above Fig. 10

and with Figs. 5 and 9 to the immediate left of Figs. 8 and 10, illustrate diagrammatically, the apparatus and circuits of the dispatchers station of the alternative form of the invention.

In both types of systems the dispatchers office and all of the stations are connected together by means of a three-conductor line circuit which extends throughout the system. The line circuit is arranged to be supplied with current supplied by a line battery Vlocated at the dispatchers office, and under' normal condition supplies negative potential to the line conductors lv and 3 and positive potential to the common return conductor 2, At each field station, as well as at the dispatchers station, relays are included in series with the conductors I and 3, and the common return conductor 2-,` and these relays control `the apparatus at their respective stations to perform all functions necessary for thetransmission and receiving of signals over the system.

` The various relays diagrammatically shown throughout the drawings, except for the polar relays,A are of the general type ordinarily em ployed in automatic telephone systems. 'I'he polar relays are of the stay-put type, i. e., their armatures always remain Vin their last operated position.

'I'he sender switches SS, SS',` SS2, and S83, are of the well-known single-motion pawl-andratchet type, arranged to advance-their wipers upon each'deenergization of their motor magnet.

The mechanisms of the incoming selector switch IS and of the minor switch M are also of the well-known single-motion pawl-and-ratchet type, but diier from the sender switches in that they always advance their'wipers upon the energization of their motor magnets, and are p rovided with release magnets which function, when' energized,- to permit their wipers to' restore under tension of their restoring springs.

I'he connector switches C Vand D', employed to select the polar relays, are of the well-known Strowger typ'e;

It is believed that a Inost thorough understandingof the invention can be attained by describing the operation of the system.

Referring now particularly to the field station circuits and apparatus, comprising Figs. 1 to 4, it is assumed that all switches are at normal, and

that all of the relays in the eld station are in the position shown.

The relay ||6 of the tell-tale relay group is energized and locked by way of the upper contacts of the customers relay |00, because of a previous operation. The relay 201 of the miscellaneous relay group is energized because it is the from-the-i'leld line relay of this station and is included in a normally-closed line circuit including all stations of the system. This circuit may be traced from the negative side of the line battery at the dispatchers board, Fig. 5, over the No. 1 line to the dispatchers line relay 800, No. 1 line in extending to the eld station, through contacts of the station cut-out switch SI, through the winding of the eld relay 201, the lower-break contacts of relays 2I5 and 2|0, respectively, through switches SI and S2, respectively, out over No. 1 line out, through the line relays of the succeeding field stations, not shown, and back over the No. 2 line, through the last station switch S2, to the No. 2 line in to positive potential at the dispatchers station.

The polar relays P and P are magnetically held in the position shown, because that happens to be their last operated position.

Field station tell-tale relay operation It will now be assumed that the armature of the customers relay |00 moves to its lower position. When this occurs, the relay IIS becomes deenergized, because of the opening of its circuit, which, as previously stated, included the upper contacts of the customers relay |00. The deenergization of relay l I6, is, however, without effect at this time. The relay I|8 becomes energized over the circuit extending from positive potential supplied through the lower contacts of the customers relay |00, the break contacts of relay I I9,

v.the inner-upper contacts of relay I I8, the winding of this relay, its lower-break contacts, pick-up conductor 220, and through the break contacts of relay 20| and the upper break contacts of relay 202 to negative potential. The relay I I8, upon operating, completes a locking circuit for itself which includes the winding of relay 20|, conductor 222, the upper-break contacts of relay I2 I, the upper-make contacts of relay IIB, its winding and its lower-make contacts, conductor 22|, and the upper-break contacts of relay 202 to negative potential.

The relay 20|, accordingly, operates and at its upper contacts removes negative potential from the tell-tale relay pick-up conductor 220. VThe tell-tale relay ||8 also, at its three lowermost contact sets, connects positive potential to the conductors |36, |31, and |38. These conductors extend by way of the cross-connecting frame 300, and by appropriate jumpers thereat to the rst, third, and fourth bank contacts, respectively, of the rst, second, and third-digit banks 35|, 352, and 353, thereby marking the code |34 on the sender to be subsequently transmitted. Furthermore, the relay ||8 at its inner-lower make contacts prepares the circuit of re-set relay I9.

Field station miscellaneous relay operation The relay 20|, in addition to breaking the common pick-up circuit, for the tell-tale relays, at its make contacts completes the circuit of relay 205, which accordingly energizes and closes the circuit of relay 205 by way of the upper break contacts of relay 209. The relay 205' accordingly vibrates its contacts which eventually come to rest in closed position and in so doing complete the circuit of the slow-to-pull-up relay 200.

The relays 205 and 206 aord a delay feature, i. e., the time elapsing between the energization of relay 205 and the energization of relay 206 may be anywhere from one-tenth second to two seconds, depending upon the adjustment. At this time the delay feature has no apparent function',A but the necessity for it will become apparent when a discussion is entered into concerning the lock-out feature.

The relay 206, upon operating, closes the circuit of relay 2|0, by way of the make-beforebreak contacts of relay 209, conductor 232, the break contacts of relay 3|6, and conductor 23|. The relay 2|0, upon energizing, at its break contacts opens the No. l line; which, as previously explained, includes the from-the-eld line relay 281 at each eld station; at its inner-lower contacts closes a point in a locking circuit for itself, at its upper-make contacts prepares an operating circuit for the sloW-to-pull-up relay 2 I1 and a locking circuit for the relay 2|6, at its lowermost make contacts prepares the pulsing circuit which will subsequently be employed by the sender SS in transmitting a code back to the dispatchers station, and at its middle-lower make contacts closes a point in the sender start circuit and completes the circuit of slow-release relay 2| 3. 2|4 and 2| 5, respectively, operate in sequence, but their operation will be without eicct at this time.

consequent to the opening of the No. l line, the line relay 201 becomes deenergized and at its break contacts completes the circuit of slowrelease relay 208, which, in turn, completes the circuit of slow-release relay 209. This latter rclay, upon operating, at its lowermost contacts completes a locking circuit for relay 250, which is independent of the contacts of relay 206. This circuit extends from positive potential supplied through the break contacts of relay 2|2, the inner-lower make contacts of relay 2 i0, the lower make contacts of relay 209, conductor 232, the break contacts of relay 3|6, conductor 23|, and the winding of relay 2|0 to negative potential. The relay 209 also, at its upper contacts, opens the circuit of relay 205'; thereby permitting this relay and its associated relay 200 to restore to normal; and at its upper-make contacts completes the circuit of relay 2I1 by way of the upper-make contacts and upper-break contacts of relays 2I0 and 2|6, respectively.

The relay 2|1, upon operating, closes the same circuit to the relay 2|8 which, accordingly, energizes, and at its lower contacts closes a circuit from the No. 2 line in by way of the lower make contacts of relay 2|0, resistance X, and the Winding of from-the-eld line relay 201 to the No. l line in on the dispatchers side of this station. The relay 281, accordingly, becomes energized again, thereby causing the energization of relay 2|6 over a circuit including the makecontacts of relay 201, the upper-make contacts of relay 208, and the upper-make contacts ci relay 2|8. The relay 2|6, upon operating, at its upper contacts interrupts the formerly-traced circuit of relays 2I1 and 2|8 and completes a locking circuit for itself including the upper contacts of relay 2|0 and the upper-make contacts of relay 209. The relay 2|8, upon restoring, at its inner-lower make contacts again opens the circuit of relay 2| I, and at its lowermost contacts again separates the No. 2 line in from the No. l

This latter relay and the associated relays Afn lineiinf. Z'I'hedeenergizationof the fr'omsthefield fline `relay :207 fand-of the -other from-theeld `line :relays between theactive eld station and the .dispatohers .station is thereby brought about.

,Before :goingfahead .with a 'description of the operation of thesender, itmay ybe explained that the relays 2H and l2l2 .provide a delay `feature operative :from V.relay 2l'8 :and constitute part of the .lockout circuit whichwill be described subsequently. However, in the normal operation, relay I2:l2idoes not havetime to `function before the relay 2 I8 has lreleased again.

.The foregoing `operation of relays 2 i l, 2l3, and

246 has fthus Vresulted in `a singlepulse, of ap-V proximately two-tenths second duration, being delivered by the from-the-eld line'relays, such as 201 between the `sending field station and the dispatchers station, and `is `termed. the preliminary pulse.

It may be mentioned that the compensating resistance X is introduced Yinthe pulsing circuit to take the `place ofthe disconnected field line relays beyond -this station, thereby maintaining the normal milliampere flow 4inthe No. l line.

.Relay `2 I6,-uponlenergizing, as before explained, at its uppermost break contacts interrupts the circuit of relays 2H and 218, thereby fore-stalling the voperation of .relay -2t2 (the foregoing operation having taken place within the delay time ofrelays 24.6 and -2-l2) completes a locking circuit for itself at its upper-make contacts, and at its -1ower-make contacts completes the sender start circuit. This latter circuit extends from positivepotential supplied through the middlelower contacts of rrelay 210, the lower-make contactsof relay Y'.ZI6, conductor 23e, and the Winding of sender relay`304 to negative potential.

Field sender switch operation The relay 304 closes rits contacts after a slight of relays 3.04 kand Y305 is to introduce a delay of a suitable interval, after the release of the eldY line relays, such as 201, for the completion of the lockout function, and for the preparation of the dispatchers incoming circuit,

The relay 306, upon operating, at its innerupper contacts, closes a circuit for the relay 332 by way of the upper-break contacts of cut-off relay 308 and the break contacts of Vrelay titl, at its 'lowermost contacts prepares the locking circuit of relays 3l2 to 3HE, inclusive, at its uppermost contacts prepares the homing circuit for the sender switch SS, .and at its inner-lower contacts prepares a locking circuit for the relay 301 and a Vsecondary locking circuit for the cutoff relay V308.

The relay 302 becomes energized over the pre-` viously traced circuit, at its 'lower contacts completes vthe circuit of relay 303, and at its upper contacts completes a locking circuit for itself includingtthe break :contacts of relay 33t. The relay y303, upon operating, at itsinner-lower make contacts completes the circuit of relay which, in turn, opens the circuit of relay 332. The relays ,3U-I, 302, `and 303, accordingly, interact so long `as vthere is positive potential supplied to them through the middle-upper contacts of the cut-off ,relay 308.

Each -time the relay 303 ener-gizes, in addition to closing the circuit of the relay Stil; at its lowermost contacts it transmits `pulses from the No. 2 :line-supplied with positive ipotential 5at :the dispatchers :station ,over `conductors 22B :and `226 through the lower-break contacts of Vrelay 308, through "the lowermost make contacts .of relay Zilli, compensating `resistance X, .and 'through .the winding of line `relay 207, to the No. 1line,which, as previously explained, also passes through the from-the-eld line relays v20'! of all 4field stations intermediate to the sending station and the dispatcher, and which then extends through the from-the-eld line relay 800 at the .dispatchers station to the negative terminal 'of Ithe' line battery.

These pulses, accordingly, operate the linereiay 20? and the corresponding line relay Vat each i5 field station intermediate to the `sending station and the dispatcher. The line relays, through the medium of their resting contacts, maintain their associated slow-release relays, such as 208 and ZES, energized during the pulsing operations be zo cause lof their `slow-to-release characteristic.

The relay 303 at its upper contacts `also transmits pulses direct tothe motor magnet 33! of the sender switch, causing the latter to take one step for each pulsedelivered into the No. .fl line. 25

At the first stepof the sender switch, the off- Ynormal springs ON close, thereby .causing the energization of the slow-release relay 309, which, in turn, completes the circuit of relay 320 and it, in turn, the circuit of relay 3M. 3i l, upon operating, prepares a primary locking circuit for the relay 308.

When the marked Contact, in this instance the first, `is reached by the vwiper of the first-digit bank rl, the `positive potential is applied over 35:

theconductor i371, extending .from the tell-tale relay H8, through the cross-connecting frame 303, the first-digit bank 35i, and its associated The relay 3) Wiper, to the conductor 36|, and -through the break contacts of -relay 3l=2 and through the winding of cut-off relay 30@ vtonegative potential. The relay 308, upon energizing, at its lowerrnost contacts opens the pulsing circuit to the No. 1 line, at its upper break contacts `also opens the circuit extending to the relay 332 of the pulsing group, at its inner-upper contacts completes a locking circuit `for itself, and at its uppermost contacts completes the return-to-normal circuit for the sender. This latter circuit extends from rpositive potential at ythe off-normal contactsON, through the uppermost contacts of relay 338, the uppermost contacts .of relay .303, through the break contacts of the motor magnet 33, and `through the winding of this maghetto negative potential. The motor magnet will, therefore, operate in abuzzer-like manner to advance the wipers of the sender to their normal position, at which time `the off-normal springs ON open and stop the sender in this position.

The slow-release .relay 339 also deenergizeso Y consequent to Vthe opening of the ofi-normal springs GN. Howevenin the interval between the `time the wiper of the transfer bank 353 reaches .its normal `Contact land the restoration of .the contacts of relay, 33S, circuit is closed 65 from positivepotential on ,the wiper of the transfer bank 35e Ain its normal position, through the upper-make contacts of relay 339, the upperbreak contacts of `relay 3i3,.and thro-ugh the winding of relay 3l?, to negative potential. The 70 relay Brt, accordingly, operates and Vat its lower contacts prepares the circuit of relay Sie?, vand at its upper contacts transfers the control circuit of `cut-ofi .relay Giel! from connection with the conductor 333 .and Vthe associated first-digitbank 35 l, 7:5

by way of the break contacts of relay 3I4, to the conductor 362 extending to the wiper of the second-digit bank 352.

As soon as the contacts of the relay 309 restore, the relay 3I3 becomes energized in series with the relay 3&2 over the circuit including the lower contacts of relay 306. Upon the energization of relay 3I3, this relay transfers the counting circuit from connection with the relay 3I2 to the relay 3M, by way of the break contacts of relay SI5.

Returning to a consideration of the action of the off-normal springs ON, it will be remembered that the relay 300 deenergized shortly after the sender returned to normal, thereby opening the circuit of the slow-release relay 3I0, which, in turn, opens the circuit of the slow-release relay 3i I. The relay 3i I, upon deenergizing, at its contacts opens the locking circuit of the cut-oli` relay 303, which, accordingly, deenergizes and causes the sender to transmit the second digit of the code. At this time the relay 300 is associated with the wiper of the second digit bank 352, and when the marked contact is reached, positive potential is applied over the conductor |38 extending from the tell-tale relay IIS, through the cross-connecting frame 300, and the third bank contact of second-digit bank 352, its associated wiper, the conductor 362, the break contacts of relay 3M, the upper-make contacts of relay 362, and the winding of cut-01T relay 308 to negative potential.

The rel-ay 303 will, accordingly, again operate, as before, to open the No. 1 line circuit to prevent the transmission of further impulses thereover, and this time three pulses will have been transmitted.

The sender switch will now return to normal, in the manner previously described, and when the same reaches normal the relays 3I4 and 3I5 will operate, in substantially the same manner as did relays SI2 and 3I3 at the termination of the first digit of the code. The relay 3 I4, at its upper contacts, transfers the lead extending to the cutoff relay 308 from connection with the,conducto1' 332 of the wiper of the second-digit bank into connection with the conductor 303 terminating in the wiper of the third-digit bank 353. The relay 3l upon operating, at its upper contacts extends the counting circuit into connection with the relay 390, and at its lower contacts closes a point in a secondary locking circuit for the relay 308.

Upon the deenergization of relay 3l I, which, as previously explained, follows the deenergization of relays 300 and 3l@ consequent to the opening of the off-normal springs ON, the sender switch functions to send the third digit of the code. As soon as the off-normal springs ON have become operated, the relay 300 again becomes energized and at its lower contacts again completes the circuit of relay 3I0 and in addition completes the circuit of relay 301 by way of the lower contacts of relay 3l5. Consequent to the operation of relay 3&0, relay SII also operates to again prepare the locking circuit of the cut-off relay 308. The relay 301, upon operating, at its contacts completes a locking circuit for itself and pre pares the secondary locking circuit of the relay 338, by extending its own locking circuit from the lower contacts or" the relay 306 to the relay 350, thus making the relays 3I0 and 3| I, as well as relay 308, independent of relay 309.

Since at this time the relay 308 is associated with the Wiper of the third-digit bank 353, when the fourth bank contact, which in this instance is the one which is marked, is reached, relay 308 will operate as before to cut-off and prevent the transmission of more than four pulses to the No. l line.

The code is now completed, and the sender must not again function following the deenergization of relay 300. For this reason, the relays 3I0, SI I, and 301 have been locked up through the inner-lower contacts of relay 306, as previously described.

Following the transmission of the third digit, and the restoration of the sender, and just prior to the deenergization of slow-release relay 309, the relay SIG is energized from positive potential supplied through the wiper and normal contact of transfer bank 350, over the previously-traced counting circuit. The relay 3I0, upon operating, at its inner-lower contacts completes a locking circuit for itself including the lower-most contacts of relay 306, at its uppermost contacts it places positive potential upon the re-set conductor 332, which extends to the winding of reset relay 204, and at its break contacts opens the circuit of relay 2I0.

The relay 201i, upon operating, at its lower contacts completes the circuit of relay 203 by way of the lower-break contacts of relay 202. The relay 233, accordingly operates and prepares the circuit of relay 202. The relay 204 also at its upper contacts, places positive potential on the common re-set conductor 250. This positive potential passes through the inner-lower closed make contacts of the relay IIE, through the lower winding of re-set relay H0, to negative potential. The reay IIS, accordingly, energizes and completes a locking circuit for itself including its upper contacts and the contacts E35 of the customers relay E00. The operation of relay IIS is otherwise without effect at this time.

As previously mentioned, the locking circuitv of the relay 2 I 0, of the miscellaneous relay group, is opened at the break contacts of relay SIS. The relay 250, accordingly, at its middle-lower make contacts, opens the circuit of relay 304 of the sender, whereupon this relay opens the circuit of relay 305, and it, in turn, the circuit of relay 306, and these relays, accordingly, also restore. 'Ihe relay 305, upon restoring, permits the restoration of the remaining operated relays of the sender as will subsequently be described. The relay 2I0, also, at its inner-lower contacts, opens a second point in its own locking circuit; at its upper contacts opens the locking circuit of relay 2I0, and a point in the operating circuit of relays 2I1 and EIS, which relays have previously been deenergized; at its middle-lower make contacts also opens the circuit of slow-release relay 2I3, with the consequent deenergization of the associated slow-release relays 2li! and 2I5; at its lowermost make contacts opens the pulsing circuit; and at its lowermost contacts re-closes a point in the No. 1 line circuit. This latter operation is without effect at this time, as the line is still open at the lower contacts of slow-release relay 2I5. After a delay interval introduced owing to the slow-release characteristics of relays 2I3, 2I4, and 2IEi, the No. l line is again closed at the lower contacts of the latter relay. When this occurs, the line relay 201 will again become energized, and will again open the circuits of its associated slow-to-release relay 208, which, in turn, opens the circuit of slow-to-release relay 209. This station has thus released the line,

station.

`also restores. r

.accessi which may now. be

The slow-to-release relays 2;l.3,2i4,y11 i 2-115 ,the last `digit of the code and the reeenergization of the line `relays for the last counting relay ,operation in the dispatcheris incoming :selector IS,

Returning to a consideration .of the release of 'the sender relays, as mentioned Qoullug consequent to the release of relay 94, it .will be seen that consequent to the release of this relay, relays 35 and'SU' also become deenergized. The

.relay 3.6.6, `in turnfonens thefcircuit extend-ine t0 the r relay @c2 of the pulsing group, `and ythe homfng .circuit of .the .sender Switch, which, however,

are already opened at this time.. .lay ,3&5 also byopening rits lower contact sets C uses the release of relays 301, 3|0, and SI2 toiliii, iinclusive, Consequent to fthe deenergiationiof relay 3 id relay 3 l l `also :deenergijzesiandopens .the .611"- cuitof the cut-oirrelaylBU, whicnaccordingly,

also restores. v

'I'he .relay g'ii, Lupon zrestoringzat its :upper .Qon-

itacts, again opens the circuit of relayZUA of the miscellaneous relay group, Vand .this relay, accordingly, .also becornesdeenergized. The relay 204, upon deenergizing, removes lpositiue pot.en

tial `from :the lower `'terminal of relay 202,1ar1d this relay accordingly lenergizes -fin Series with the relay 203 .toopenthe lockingicircuit .of.the tellstale .relay H 8. Shortlyafter this, miscellaneous relay i215 releases, landfat `fits v:upperlcontacts opens the circuit .of .relays :'202 4and :20.3, thereby 'permitting `them to -resto're :to inormal.

The .relay gli l, which `was vheretofore energized 2in series :with the tell-tale relay '|'-|='8, accordingly,

.Second field telZ-tcle rclayyopemtiot y `j If, `previous to the-operation fj-ust described, -a 4second signal relay has"becorn e operated, its

vassociated -te1lt ale"relaywill energize upon the release of 'tell-tale relay A-Hand -rniscel'laneous relay 21H, whereupon Vthe miscellaneous relay Jgroup Vwill again 'function Ato -atternpt to seizethe line, and, if successfulwill start the sender to sendthe codeirnarked -by the newly-operateditell- ,tale relay.

To the field Operation When the dispatcher seizes thedindllgylllting a key representing a function to he `performed in une eidas will subseeuentiy 'liede- ,of the minorswitchlM.

Ityvill `be assumedthat the key-,operatedpythe ,dispatcher causes ,the 4,transmissiein ,of -the lcode 0.01, thadieits of the @desem-prisme itenrnulses. .The line relayt svi-11., accordingly, respond vto `eachoftheiteri.pulsescomprising ther The fslcwetofrelease :relay v4.0 A9., non .f fall 4 away during .the :momentary i' ,te untiolls .f of 1' ts circuit, land, thereto-12e, at reach operation series of pulses, relays .411| vvsieenergized. The flatter relay,

".mipalsfof lthefrelays litt, 453.4, and riagoord'nely,enereiaes in -series with the .relay M3.

of Vth p :The second `Series of cfrelay 4il0 a circuit is closed by IWayof its `front contacts, the front contacts of relay! l, the low- ,er-breakcontacts of relayllu, tothe slowfrelease rela-y .40| and negative potential. A .branch .of this .circuit also extends by way of :the lower Abreak contacts of relay tijd through .the magnet M5 .of 'the minor switch [M potential.

.Consequent .to `the .transmission -of the .ten `impulses comprising the ,first digit Q the Vminer to negative switch rotates itswiper e553 intoengagenient with 49.4, The relay-lit, .upon operating, extends :the r- 5positive potential, applied to the upper terminal of relay 403, rto the upper terminal of grelay, but Without Veect at this time since there lis already positive potential connected with the lower terminal of this relay.

At :the termnationof the transmissionof the and ,4.02 `become upon restoring,

removes positive potential from the upper Iterrhesrelaynq, upon operating, fat its upper con- ,tacts transfers the counting circuit'fromiconnec- V,tion with the terminal of relay 493.into connection upper break conr A .tacts oiirelayiltsandatits lower contactsatransfers ,the pulsing circuit `branch formerly .extending ,to lmagnet `H5 into connection :with the iWP-f' '55,91 :Whl'ClL CQllSCquent .tothe transmission l e rst digit, :has been positioned fin engage- With its ten-th .bankcontacu and which :has uit extending vtherefrom through :to the cal; .contacts of relay .,406 .to the ...Vertical 1 of the-,Strowger switch. pulses received :by the line relay Aoi) lwill, accordingly, .be transmitted .energization r`of relay 403 upon :the termination ofithetrcnsmissonof thefsecond. digit. Therelay A55, .llvDQn .Qperatingextends the` counting circuit to tile delayfl by .Wayof I the .f upper contacts of 11i-lay ilnandat its flower contacts ,itrarlsfers the pulsing circuit from connection Ywith the vertical magnet 4H of the connector'into connection with VCcnsequen-t tothe trans- .mission .of the .second ipulses, the connector wiper 15.25 is eleVa-tedopposite the tenth level of its bank contacts.

The next and final digit of the code comprising one pulsecauses the rotary magnet gli! 5to position thew'iper into connection ,wth thenrst bank contact in the tenth'level of its bank, and the energization-.of relayaiiill aslbefore. This time ...the Iaescoated relay .4.012, 11.100 operating, @0mthrouehout the series thelatter relay, i

digit, comprising ten v-im- 1&0

.prepares the` operating ,Circuitof relay-40@ A termmatien of the transmission -of the.

non bird .d .digit ofathefeode,ftheirelay lllbeo mes Y.energizfai in fseries Withlrelay Aal. Relay A118.

:upon -sinner.ating, :at-its `upper QQHtaQtsoDens che counting circuit and at its lower contacts opens the pulsing circuit.

When the relay 402 deenergizes following the last operation of rotary magnet 418 the coil 426 of the polar relay P becomes energized from positive potential supplied through the breakcontacts of line relay 400, the break contacts of slowrelease relay 402, and the wiper 425. The armature and contacts of the polar relay P will, accordingly, assume the position alternate to that shown, thereby closing the operating circuit of the customers equipment, as required.

The code to the eld is now complete and the dispatchers equipment will again close the No. 3 line, thereby energizing all to-the-eld line relays, such as 400. Consequcnt to the energization of relay 490, its associated relays 409 and 410 will again become deenergized. The relay 410, upon restoring its contacts, interrupts the locking circuit of the counting chain comprising relays 403 to 408, inclusive, thereby permitting these relays to restore to normal, and at its lowermost contacts applies positive potential by way of the off-normal springs ONS to the release magnet 120 of the connector C, and by way of the off-normal springs ONS to the release magnet 416 of the minor switch M, and these switches, accordingly, restore to their normal position.

It may be explained that the minor switch at each field station will respond to the first digit,

but the second and third digits of a code will be ineffective except for such connectors, in this instance, those having a pulsing circuit which is led through the tenth contact of their associated minor switch, and only one of these will nd a polar relay coil associated with bank contact 001. It should also be noted that the wiper 425 of the Strowger switch is open during the rotation at the lower contacts of relay 402, so that no polar relay will be operated while the wiper 425 is passing from one bank contact to another. It may be also noted that during the release operation of the switch positive potential is removed from connection with the wiper 425 at the break contacts of line relay 400, so that improper operation of a polar relay cannot occur at this time.

Field locks out field It will now be assumed that a eld station seizes the line, in which event all other field stations are locked out, but there is a slight difference in the manner of locking out, depending upon whether the trying field station is between the one which has seized the line or whether it is beyond the station which has seized the line.

Trying station between break springs of relay 209 being opened.

Trying station beyond In accordance with the foregoing assumption, miscellaneous relay 210, of the station which has seized the line, has opened the No. 1 line at its lowermost contacts. Therefore, the line relay 201 in all of the beyond stations is deenergized, while the associated relays 208 and 209 thereof are energized. A beyond station is, therefore,

KAlocked out because there can be`no circuit estab- Simultaneous yield operations Two field stations may function so that their relays 210 of their miscellaneous relay groups become energized simultaneously. The station near the dispatcher will function normally and seize the line. The beyond station will lockout as follows:

'I'he line relay 201 will be deenergized by the operation of the relay 2I0, as in the normal operation of seizing the line. The relays 208 and 209 will, accordingly, operate in the usual manner, and the relay 209 will complete the circuit of slow-to-pull-up relay 211, and subsequently relay 218. The relay 218, upon operating, at its lower contacts, will attempt to send the preliminary pulse to the line relay 201, as in the normal operation, but cannot do so because the No. l line has been opened at the nearer station by the operation of its relay 210. Therefore, 'n

since the relay 201 of the station beyond does not receive the required preliminary pulse, it cannot complete the circuit of relay 216, as it does in the normal operation of seizing the line. Owing to the fact that relay 216 fails to energize, the

circuit to slow-to-pull-up relays 211 and 218 is held closed for a sufficient period to allow the operation of the associated relays 211 and 212. This latter relay, upon operating, interrupts the locking circuit of the associated relay 210. The

relays 211 and 218 are slow-to-pull-up to allow ample time for the energization of relays 208 and 209 before the station tries the preliminary pulse.

The relay 210, upon deenergizing, at its upper contacts opens the operating circuit of relays 211 and 218, thus locking out this station. Relays 211 and 212 will release in turn upon the deenergization of relay 218, and all relays in this station will be once more in their normal position, with the exception of the operated tell-tale relay and relays 201, 201, 208, and 209 of the miscellaneous relay group.

When the line is again free, the energization of the line relay 201 and the release of relay 209 of the miscellaneous relay group will again cause the relay 205 to try the line. If it is successful in causing the energization of relay 216 all other stations are locked out until after the completion of the transmission of the signal from this station.

Circuit operation of the dispatchers station equipment Referring now to the dispatchers station .1'.

equipment comprising Figs. 5 to 8, inclusive, wherein all switches are in their normal position, the tell-tale relay 616 is energized because the first operate key is positioned in engagement with its lower contacts. relay 800 is energized because it is the fromthe-eld line relay. The polar relays P3 and P4 of the return indication polar relay group and the polar relays P5 and P6 of the automatic indication polar relay group all have their armatures The incoming selector if Tell-mz@ relay iteration at ma dispatches station Consequent to movement of the rst operate key, the tell-tale relay GIG will become deenergized, but without elect at this time. The telltale relay GES will operate from positive potential supplied through the rst" operate key its contact O01, conductor 559, the break contacts of relaytlQ, the inner-upper break contacts of relay l, the winding oi this relay, its inner-lower break contacts, the pick-up conductor 62E), through the break contacts of relay Gill, the upper-break contacts of relay 692, to negative potential. The relay M8, upon operating, completes a locking circuit for itself including the relay GGL This circuit extends from positive potential, through the winding of relay Gill, holding conductor 22, the upper-break contacts of relay 52i, the upper-make contacts of relay M8, its winding, its lower make-before-break contacts, conductor 62H', and throughV the upperbreak contacts of relay 6&2 to negative potential. The relay Slt also, at its inner-lower make con-V tactsprepares an operating circuit for the reset relay tig, and at its three Vlowermost sets of contacts applies marking potential to conductors 636, 531, and @38, terminating in the cross-con-V necting frame lilo. These conductors are furtherrconnected by means of jumpers to the tenth bank contacts of the nrst and second-digit banks 75l, 152, and to the rst bank contact of the third-digit bank l53 of the sender switch SS.

The relay 66E of the miscellaneous relays op-Y erates over the traced circuit; at its upper contacts interrupts the common pick-up circuits for the tell-tale relays, so that no other tell-tale relay can operate until the first-operated tell-tale relay has been restored and the relay 6U! deenergized.

' Operation of the miscellaneous relays at the dispatchers station In this form oi the invention the dispatcher at all times has access to the eld stations, therefore, the relay tti at its lower contacts transmits positive potential to the relay Eile of theY sender direct.

Operation of the dispatchers sender The relay lili, upon operating, at its break contacts opens the No. 3 line, which, at the 'dispatchers station, includes the lower-break contacts of relay 'l2i, conductor 653, the lower-break contacts of relay its, and then extends as the ,l\To. 3 line out, and at its make contacts completes the sender start circuit which extends from positive potential supplied thro-ugh contacts 'of relay left, the lower-break contacts of relay No. 3 line and the starting of the pulsing oper-Y ation. The relay it, upon operating, at its up- Y per-make contacts completes a circuit by way oi the upper contacts of relay 722 and by way of the contacts of relay lo! to the relay 702 and negative potential, causingl this relay and its associated relays lEBl and 'm3 to inter-act to operate the sender SS and to transmit pulses over the No. 3 line in the same way that these operations are performed by similar relays 3M to 353 in the sender of the field station. rI'he relay lli also, at its inner-lower contacts, prepares the return-to-normal circuit of the sender, at its middle-lower contacts prepares a locking circuit for relay lll, and at its lowermost contacts prepares a locking circuit for relays H5 to ll, inclusive, and for relay @lill of the miscellaneous relays, and at its inner-upper contacts completes the operating circuit of the slow-release relay 725. This latter relay, upon operating, causes the operation oi slow-release relays '126, l2?, 128, 729, and il il in sequence.

At the first step of the sender switch SS offnorrnal springs ONSEZ close, thereby completing an energizing circuit for the slow-release relay lll. This relay, in turn, causes the energization of relays M2 and iis, respectiveiy. When the wiper of the first-digit bank 'ii reaches the tenth bank contact ten pulses have been transmitted over the No. 3 line and the wiper picks up positive potential originating at the make contacts of the operated tell-tale relay SEB, and supplied through conductor ttl and through the cross-connecting frame 'ili to the tenth contact of the bank lil, through its associated Wiper ll, the break contacts of relay H5, and the winding of cut-off relay i222 to negative potential. The relay 722, accordingly operates; at

-its lower-break contacts opens a point in the No. 3 line circuit to'prevent the further transmission of pulses thereover, at its upper-break contacts it opens the circuit extending to the pulsing relay group, at its inner-upper contacts completes a locking circuit for itself including the oir-normal springs ONS?, the lower-make springs of cut-oil relay it, the inner-lower make springs of relay Sd, and the interruptor springs and rotary magnet l3l of the sender switch.

The motor magnet iti will now act as a buzzer and return the sender switch to normal position, at which time the off-normal springs ONSZ again open the circuit to the motor magnet, and to the associated slow-release relay lil. Relay iii accordingly, restored, bringing about the restoration of slo-w-release relays i l2 and lit, respectively. The relay H3, upon restoring, opens the locking circuit of cut-oli relay i222, thereby permitting it to restore. The slow-to-release relays 'll l, "M2, and H3 provide the necessary time interval between the-digits which is necessary'to allow connector relays 5&9 .and lili, at all field stations, to deenergize.

When the wiper associated with bank 756 of the sender reaches its normal Contact, the energizing circuit of relay H5 is closed by way oi Vthe upper-break contacts of relay il@ and the make contacts of slow-release relay lll. This circuit is opened when the relay lil deenergizes, whereupon the relay llt will energize and lock up in series with the relay H5.' The Yrelay H5, upon operating, at its inner-upper contacts prepares the operating circuit of relay liti, and at its upper contacts transfers the control of cuton" relay H2 from connectionwith conductor 

